1) Field of the Invention
This invention relates generally to fabrication of semiconductor devices and more particularly to a lateral double diffused metal-oxide-semiconductor (LDMOS) and the fabrication of same.
2) Description of the Prior Art
Today's integrated circuits can include a huge number of transistors, capacitors, or other semiconductor devices formed in a semiconductor. Smaller devices are the key to enhance performance and to increase reliability in devices. As devices are scaled down, however, the technology becomes more complex and new methods are needed to maintain the expected performance enhancement from one generation of devices to the next. This relates mainly toward the primary semiconducting material of microelectronics, namely Silicon (Si), or more broadly, to Si based materials. One of the most important indicators of device performance is the carrier mobility. There is great difficulty in keeping carrier mobility high in devices of the deep submicron generations. A promising avenue toward better carrier mobility is to modify slightly the semiconductor that serves as raw material for device fabrication. It has been known, and recently further studied that Si, strained in tension, has intriguing carrier properties. Mechanical stress in the channel region markedly influences the performance and reliability of MOS devices.
It has been known that a nitride etch stop film causes tensile stress in the Si substrate. Thus, there has been a lot of interest in high-stress nitride etch stop film in the fabrication of MOS devices.
Tensile stress may be obtained by forming a nitride etch stop to create stress (that translates to strain in the underlying silicon) in the channel of a MOS device. Device mobility has been extensively studied by introducing strain in the channel. One such technique is the use of contact etch stop nitride layer as a stressor. To achieve increased drive current via increased carrier mobility and velocity, thicker nitride layers may be used to meet higher, specified stress levels. The current methods of producing semiconductor device can be further improved upon.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering the following.
US 2006/0009041A1 to Iyer, R. S. is entitled Silicon Nitride Film With Stress Control.
US 2005/0266632A1 to Chen, Yun-Hsiu is entitled Integrated Circuit With Strained And Non-Strained Transistors, And Method Of Forming Thereof.
U.S. Pat. No. 6,828,628 to Hergenrother, John Michael is entitled Diffused MOS Devices With Strained Silicon Portions And Methods For Forming Same.
US 2005/0026332A1 to Fratti, Roger is entitled Techniques For Curvature Control In Power Transistor Devices.
US 2005/0221566A1 to Curello, Giuseppe is entitled Enhancing Strained Device Performance By Use Of Multi Narrow Section Layout.
The article entitled “High Frequency Power LDMOS Technologies For Base Station Applications Status, Potentials, And Benchmarking,” to G. Ma, et. al., IEDM Tech. Dig., pp 373-375, 2005.
The article entitled “High Performance RF Power LDMOSFET's For Cellular Handsets Formed In Thick-Strained-Si/Relaxed-SiGe Structure,” to M. Kondo, et. al. IEDM Tech. Dig., pp 377-379, 2005.
The article entitled “Mobility Enhancement: The Next Vector To Extend Moore's Law,” IEEE Circuits & Device Magazine, pp. 18-23, September/October 2005.